Bosch Greentherm T9800 SEO199

Questions and Answers

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William SullivanJul 31, 2025
Why is my Bosch Water Heater not heating water enough?
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  Jessica BautistaJul 31, 2025
  If the water from your Bosch Water Heater isn't hot enough, here's what you can check: * Ensure the selected temperature on the unit isn't set too low. * Confirm that the heater's gas type matches the type of gas being supplied. * Inspect the inlet gas particle screen for any blockages at the gas connection on the bottom of the unit. * Verify that the gas pressure is within the specified range. * Also, consider the possibility of cold water mixing into the hot water lines due to a plumbing crossover. Consulting a professional plumber may be necessary to correct this issue.
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Nicole EdwardsAug 4, 2025
What does error code EA/EC mean on Bosch Greentherm T9800 SEO199?
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  carrie54Aug 5, 2025
  If your Bosch Water Heater displays error codes EA and/or EC, it may indicate improper gas supply conditions, such as gas pressure and/or gas composition. Verify that the correct gas type is selected and that the gas pressure is within the specified range.
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David ValdezAug 8, 2025
How to fix Bosch Greentherm T9800 SEO199 Water Heater error codes C1, C2, CF, CE?
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  Ryan MccoyAug 8, 2025
  If your Bosch Water Heater shows error codes C1, C2, CF, and/or CE: * Check for any venting obstructions and remove them if present. * Try resetting the error by holding the On/Off button for 3 seconds.
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Jimmy MartinAug 13, 2025
What to do if Bosch Greentherm T9800 SEO199 has low water flow?
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  Christopher SmallAug 13, 2025
  If you're experiencing low water flow or pressure with your Bosch Water Heater, here are some potential causes and solutions: * Too many hot water applications might be in use simultaneously, or the flow demand is too high. * If the selected temperature on the unit is set too high for the demanded flow rate, lowering the selected temperature can allow the motorized water valve to open up, increasing the water flow rate. * Inspect the water path for any obstructions. Ensure that all shower heads, faucet aerators, and whole house filters are clear of debris. * In areas with high mineral content in the water, periodic descaling may be necessary.
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Rebecca KnightAug 17, 2025
Why does my Bosch Greentherm T9800 SEO199 Water Heater temperature fluctuate?
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  Melissa SmithAug 18, 2025
  If the hot water temperature fluctuates at the tap with your Bosch Water Heater, consider these possibilities: * If the water heater set point temperature is high, mixing at the faucet could deactivate the water heater. * There may be unbalanced pressure in the water lines. * Temperature balancing valves might be deactivating the water heater. * Erratic inlet water pressure could be due to fluctuating supply water pressure.
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Daniel LeeAug 22, 2025
Why is my Bosch Greentherm T9800 SEO199 Water Heater noisy during operation?
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  David TranAug 22, 2025
  If your Bosch Water Heater's burner/heater is noisy during operation, the cause might be improper gas supply conditions, such as gas pressure and/or gas composition. Verify if the correct gas type is selected and if the gas pressure is within the specified range.
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Michelle HillOct 26, 2025
How to fix Bosch Greentherm T9800 SEO199 Water Heater when burner does not ignite?
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  Laurie ParkOct 26, 2025
  If the burner on your Bosch Water Heater doesn't ignite when you open a hot water faucet, there are several things you can check: * First, if the display is blank, ensure the unit is receiving power from a properly grounded 120VAC/60Hz circuit. Verify the heater power supply and check all wire connections, including plugged connectors. * With the unit's power off and unplugged, remove the front cover and inspect the wire connections between the water valve, control unit, and electrode set. * Also, verify that the fuses in the control board are in good condition. Note that accessing the fuses requires removing the control board. * Ensure the cold water inlet connection is plumbed to the correct side of the heater (right side when facing the unit). * Confirm that there's at least ...

Summary

Key to symbols and safety instructions

Key to symbols

Explains warning symbols and their meanings in the manual.

Safety instructions

Crucial safety warnings and precautions for installation and operation.

Appliance details

Features

Highlights key features and residential model characteristics.

Specifications (Technical data)

Provides detailed technical specifications for capacity, temperature, gas, water, and dimensions.

Unpacking the heater

Steps for unpacking the heater and checking box contents.

General rules for safe operation

Essential guidelines for safe installation and operation of the water heater.

Dimensions

Visual representation and measurements of the appliance's physical size.

Installation instructions

Introduction and Location Planning

Overview of installation process, safety, and planning the heater location.

Heater Location and Clearances

Guidelines for selecting heater location and minimum installation clearances.

Mounting Instructions

Procedures for mounting the heater, including considerations for vinyl siding.

Air Openings and Factory Settings

Details on air intake, factory gas settings, and modular home mounting.

Gas Piping and Connections

Instructions for connecting the gas supply, including safety and sizing.

Water Quality and Connections

Requirements for water quality, connecting water lines, and filter installation.

Condensate Drain and Water Filter

Connecting the condensate drain and installing the water filter.

Domestic hot water recirculation

Guidance for domestic hot water recirculation with an external pump.

Space heating applications

Information on using the heater for space heating and related precautions.

Measuring Gas Pressure

Procedures for measuring static and dynamic gas pressure for installation.

Electrical Connections

Electrical Power Supply

Safety and connection requirements for the electrical power supply.

Fuse Location in Control Unit

Steps to locate and check fuses within the control unit.

Operating Instructions

Safety Before Operation

Critical safety information to review before operating the water heater.

Powering On and HMI Access

Steps to turn on the appliance and access the human-machine interface.

Error Code Reset and Temperature Selection

Procedures for resetting errors and selecting the desired water temperature.

Default Temperature and Solar Mode

Programming default temperatures and understanding solar mode activation.

Information and Adjustments Menu

Navigating the menu to access information and make adjustments.

Operation Data and Failure History

Viewing operational data, cycle counts, and failure history.

Purge Function

How to use the purge function to clear the exhaust circuit.

Settings Menu

Accessing and configuring various settings like recirculation and startup delay.

Unit Settings and Region Selection

Configuring display units, selecting the region, and recirculation settings.

Temperature Limit and Appliance Type

Setting temperature limits and defining appliance type and bypass function.

Maintenance and Service

Water Actuator Calibration

Procedures for calibrating main and bypass water valves.

Gas Type Verification

Ensuring the correct gas type is selected for appliance performance.

Required Annual Maintenance

Checklist for essential annual inspection and cleaning tasks.

Seasonal Winterizing and Scale Management

Preparing the unit for seasonal shutdown and managing mineral scale build-up.

Troubleshooting

Introduction and Burner Ignition Issues

General troubleshooting approach and steps for burner ignition problems.

Temperature and Flow Issues

Diagnosing and resolving problems with water temperature and flow rate.

Noise, Error Codes, and Gas Pressure

Addressing operational noise, specific error codes, and manifold gas pressure.

Gas;Air Flow Adjustment

Procedures for adjusting gas and air flow for optimal combustion.

Manual Gas;Air Flow Adjustment

Detailed steps for manually adjusting gas and air flow parameters.

Factory Defaults and CO Emissions

Restoring factory settings and performing CO emissions checks.

Problem Solving and Error Codes

Error Code Diagnostics

Table detailing error codes, their descriptions, and solutions.

Electrical Diagram

Schematic showing the electrical layout and component connections.

Sensor Resistance Charts

Graphs illustrating sensor resistance relative to temperature for diagnostics.

Software Menu Structure

Software Main Menu Structure

Diagram illustrating the navigation and hierarchy of the appliance's software menus.

Interior Components

Interior Components Diagram

Visual identification of major internal components with a numbered list.

Environmental Protection and Installer Checklist

Protecting the Environment

Guidance on recycling packing materials and conserving water resources.

Installer Checklist

A checklist for installers to complete and retain upon installation completion.

Bosch Greentherm T9800 SEO199 Specifications

General

Type	Tankless
Fuel Type	Natural Gas or Propane
Maximum Flow Rate	11.2 GPM
Energy Factor	0.95
Dimensions	23.5 x 17.75 x 12.25 inches
Weight	65 pounds
Thermal Efficiency	96%
Water Connection	3/4" NPT
Gas Connection	3/4" NPT
Voltage	120V
Frequency	60 Hz
Max. Water Pressure	150 psi
Activation Flow Rate	0.5 GPM
Minimum Flow Rate	0.5 GPM
Ignition	Electronic
Venting	Direct Vent
Warranty	15-year limited on heat exchanger, 5-year limited on parts
Vent Connection	2" PVC, CPVC, or ABS
Flow Rate	11.2 GPM
Maximum Temperature Rise	77°F
Max. Input (BTU/hr)	199, 000 BTU/hr